Connected: An Internet Encyclopedia
RFC 1112 - 3. LEVELS OF CONFORMANCE

Top: Connected: An Internet Encyclopedia
Up: Requests For Comments
Up: RFC 1112
Prev: 2. INTRODUCTION
Next: 4. HOST GROUP ADDRESSES

### 3. LEVELS OF CONFORMANCE

There are three levels of conformance to this specification:

Level 0: no support for IP multicasting.

  There is, at this time, no requirement that all IP implementations support IP multicasting. Level 0 hosts will, in general, be unaffected by multicast activity. The only exception arises on some types of local network, where the presence of level 1 or 2 hosts may cause misdelivery of multicast IP datagrams to level 0 hosts. Such datagrams can easily be identified by the presence of a class D IP address in their destination address field; they should be quietly discarded by hosts that do not support IP multicasting. Class D addresses are described in section 4 of this memo.

Level 1: support for sending but not receiving multicast IP datagrams.

  Level 1 allows a host to partake of some multicast-based services, such as resource location or status reporting, but it does not allow a host to join any host groups. An IP implementation may be upgraded from level 0 to level 1 very easily and with little new code. Only sections 4, 5, and 6 of this memo are applicable to level 1 implementations.

Level 2: full support for IP multicasting.

  Level 2 allows a host to join and leave host groups, as well as send IP datagrams to host groups. It requires implementation of the Internet Group Management Protocol (IGMP) and extension of the IP and local network service interfaces within the host. All of the following sections of this memo are applicable to level 2 implementations.

Next: 4. HOST GROUP ADDRESSES

Connected: An Internet Encyclopedia
RFC 1112 - 3. LEVELS OF CONFORMANCE